I. Field of the Invention
The present invention relates generally to filtering devices and, more particularly, to a filtering device which is adapted to be submerged within a fluid reservoir.
II. Description of the Prior Art
Hydraulic fluid systems conventionally include a reservoir of hydraulic fluid, a suction line for fluidly connecting the reservoir to a hydraulic pump and a fluid return line from the hydraulic system into the reservoir. The hydraulic fluid within the hydraulic system becomes contaminated during use and these contaminants must be removed or filtered from the hydraulic fluid in order to prevent damage to the hydraulic pump and other components of the hydraulic system. There have been a number of previously known fluid filtering devices which are fluidly connected to either the suction line of the reservoir or the return line to the reservoir to filter the hydraulic fluid.
In particular, there have been a number of previously known suction line filters which include a tubular cylindrical housing having one end positioned within the fluid reservoir and into which a filter assembly is slidably received. The filter assembly typically includes an elongated extension coaxially secured at one end to the filter element and upon insertion of the filter element into the housing, the filter element is spaced radially outwardly from the interior walls of the housing and is fluidly positioned between the reservoir and the hydraulic pump suction line.
One disadvantage of many of these previously known fluid filtering devices is that air is often entrapped within the filter element as the element is inserted into the housing. Large air pockets which are passed to the hydraulic system can cause excessive pump cavitation and other undesirable effects.
A still further disadvantage of many of these previously known fluid filtering devices is that the fluid flow through the filtering device is interrupted when the filter element is removed for cleaning and/or replacement. In many situations it would be desirable to maintain the fluid flow to the filtering device for the necessary periods of time when the filter element is removed from the filter device.
Still other types of previously known fluid filtering services include shut-off valves to prevent fluid flow while servicing the pumps. These shut-off valves, however, are very complex and, therefore, expensive in construction. Furthermore, these shut-off valves periodically require maintenance which requires that the entire fluid system be shut down while the maintenance is performed.
A still further disadvantage of many of the previously known fluid filtering devices is that the housing for the device which is submerged within the fluid reservoir must be specially fabricated from castings, stampings and the like. The special fabrication of the housing increases the overall cost of the fluid filtering device.
A still further disadvantage of many of the previously known fluid filtering devices is that the fluid system can continue to operate with the shut-off valve closed and without any exterior indication that the fluid supply is blocked producing the possibility of damage to the system.